The present invention relates to sewing machines in general and, in particular, to a new and useful guide device for sewing machines having a presser foot for sewing together fabric plies of unequal thickness.
Guide devices for sewing machines having a presser foot for sewing together plies of unequal thickness, including a main sole part with a stitch hole and an auxiliary sole part arranged laterally spaced from a stitch formation line and vertically movable on a shank part are known from German Pat. No. 615,718 and U.S. Pat. No. 3,146,743. They serve for the sewing together of fabric plies of unequal thickness, such as sewing the neckband of a shirt to the top collar when making a so-called two-piece collar, as well as for the uniform pressing of the two unequally thick collar components against a feed plate and stitch plate and also for guiding the work along the edge of the thicker collar component.
While it is considerably more expensive to make a two-piece collar than a so-called one-piece collar, where the top collar and neckband are made from one piece of fabric, the fit of a two-piece collar is much better, because the edges to be joined by a seam in the two-piece collar fold of the separately prepared neckband and the likewise separately prepared top collar can be given a form differing from each other such that the finished collar is given its desired three-dimensional shape by the seam connection at the differently patterned edges.
In order to obtain this quality-essential advantage in the much cheaper one-piece collar structure, it has been proposed to make the usual stiffening insert of the one-piece collar, which is to be bonded or welded to the outer fabric of the collar, with a three-part fold line zone in strips of a certain form and with a stiffness differing from the other regions. This permits the S-shape folding of the outer fabric joined to the stiffening insert along the collar fold, which corresponds to the line of separation between the neckband and the top collar in the two-piece collar and makes it possible to sew it exactly along the fold line, thereby achieving the effect of three-dimensional shaping as in the two-piece collar.